Problem: A magnetite ore containing 100% FeO4 is subjected to reduction by pure carbon in an externally heated retort. 90% of the Fe3O4 present is reduced to the metallic state while the remaining 10% is converted to FeO, according to the following reaction:

Fe3O4 + 4 C → 3Fe + 4 CO ............. (i)

Fe3O4 + C → 3FeO + CO ...............(ii)

The amount of carbon to be charged is 200% in excess of that required according to the equation (i). The reactant enter at a temperature of 260^oC and the products, both the solids and the gas leave at a temperature of 920^oC.

(i) Perform the material balance and energy balance calculations for the process on the basis of 100 kg magnetite charged. Also

(ii) Estimate the heat requirements for the process based on 100 kg of magnetite charged.

Following data are available:

Specific heats, Kcal/Kg-^oC,

Fe3O4 = 0.18  FeO = 0.18  Fe = 0.13

C = 0.30   CO = 0.27

Standard heats of formation, Hr^oC at 25^oC in kcal/gmol

Fe3O4 (s) = -267

FeO (s) = - 64.3

CO (g) = -26.4